Contributions to the Data on Theoretical Metallurgy: [Part] 11. Entropies of Inorganic Substances: Revision (1948) of Data and Methods of Calculation Page: 34
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34 CONTRIBUTIONS TO DATA ON THEORETICAL METALLURGY
The heat capacities of the two varieties of CaSO4.1/2H20 were
measured by Kelley (298) (540-2950). The entropy values obtained
for CaSO4.1/2H20(a) are S..1=2.62 (extrapolation) and S9s.16--
S53.1=28.61 (measured), making S298.1=31.20.4. For
CaSO4-1/2H20(W), S.1 = 2.82 (extrapolation), S29.16-- S3.1 - 29.26
(measured), and S29s.6= 32.10.4.
Anderson (298) (530-2980) and Latimer, Hicks, and Schutz (324)
(180-3030) have measured the heat capacity of CaSO4.2H20 (selenite).
The results are in good agreement and yield S298s6-- 46.4 0.3, the
extrapolation below 17.780 being 0.20 and the measured portion
between 17.780 and 298.160 being 46.15.
Silicates.-The heat capacity of CaSiO3 (wollastonite) was measured
by Cristescu and Simon (117) (100-2100) and Wagner (496) (90-3040).
The combined data yield Ss98.1-=19.60.2, of which only 0.016 is
extrapolation below 100.
Parks and Kelley (384) (880-2990) and Wagner (496) (100-2960)
have measured the heat capacity of CaSiO3 (pseudowollastonite).
The results of the two investigations are in fair agreement. Calcula-
tion gives S298.16=20.90.2, with only 0.013 extrapolation below 100.
Wagner (496) (200-400), in addition, has made a few heat-capacity
determinations of CaMg (SiO3)2 (diopside). The temperature range
covered is too small to permit a reasonable entropy calculation.
Titanate.-Shomate (480) (520-2970) measured the heat capacity
of CaTiO3 (perovskite). His data yield S2.00= 1.08 (extrapolation),
So8.1a--S2.00=21.30 (measured), and S~98.18=22.40.1
Element.-The heat capacity of graphite was measured by Jacobs
and Parks (227) (930-2940) and Nernst (378) (280-2840). Relying
on the work of Jacobs and Parks, there is obtained S0298 .1= 1.36 0.02
for C (graphite). The extrapolation below 89.120 is 0.168.
Nernst (387, 376) (230-2200), Pitzer (387) (700-2880), and Robert-
son, Fox, and Martin (397) have measured the heat capacity of
diamond. Pitzer's data yield S2s9.=8.10.5850.005. The extrapola-
tion below 70.80 is 0.008.
In obtaining the entropy of C(g) at 298.160, three states must be
considered--3P, 3P1, and 3P2 (864). These states have the term values
0, 14.8, and 42.3 and quantum weights 1, 3, and 5. They result in
the addition of 4.357 to the Sackur equation to obtain S298.16= 37.76
0.01 for C(g).
Available molecular-constant data (212) for C2(g), w= 1,630 and
interatomic distance= 1.312 X 10-8 cm. (1=17.2 X 10-40), lead to
S98.1 = 47.91 0.10. The quantum weight of the ground state is
taken as 3.
Monoxide.-The heat capacity of solid and liquid CO was measured
by Clayton and Giauque (73, 74) (140-850), Clusius (75) (110-820),
Eucken (146) (170-780), and Kaischew (235) (540-760). Clayton
and Giauque have calculated the entropy from spectroscopic data
as well as from the thermal data. Their results are adopted; namely,
S1.70=0.46 (extrapolation), Six.s-S.vo=-9.63 (crystals II), AS~1.5=
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Kelley, K. K. Contributions to the Data on Theoretical Metallurgy: [Part] 11. Entropies of Inorganic Substances: Revision (1948) of Data and Methods of Calculation, report, 1950; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc12637/m1/38/: accessed April 24, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.